This invention relates to a safety mounting device that may be used for mounting a member that is subject to various external forces, the safety mounting device functioning to prevent the member from being damaged if the forces should become excessive. The safety mounting device of the present invention was designed for use in robotic welding applications to mount a welding torch and will be described herein in such an environment. Those skilled in the art will appreciate, however, that this is only one of many applications to which the safety mounting device of the present invention may be put.
When a robot is used for arc welding applications, it is almost inevitable that, occasionally, the welding torch will strike some obstruction. This can be due to a variety of reasons, chief among them being operator error and equipment malfunction. Should such a collision occur, it is imperative that the robot be stopped immediately to prevent damage. Most robots can be fitted with torch contact circuits which trip the robot control in the event of the torch contacting any grounded metallic object. However, if the robot is moving at a reasonable speed, damage will occur before the robot can be stopped. Furthermore, such torch contact circuits are subject to frequent nuisance tripping as a result of weld spatter buildup, the presence of ionised gases, etc.
Even a minor collision of the torch usually results in a certain amount of displacement, requiring time-consuming reprogramming of the robot. More violent collisions can result in serious damage, not only to the welding torch, but also to the mechanical elements of the robot itself.
Various desirable characteristics of a safety mounting device for use in robotic welding applications are as follows:
1. The safety mounting device should be flexible, having compliance in as many planes as possible. PA1 2. The force required to displace the safety mounting device should be less than that which would cause damage to the robot. PA1 3. The safety mounting device should return to its preset position (home position) with repeatable accuracy upon removal of the obstruction or external force. PA1 4. The force required to displace the safety mounting device should be greater than that imposed on the welding torch by the constraints of the attached welding cables, hoses, etc. during normal operation of the robot. PA1 5. The safety mounting device should be fitted with some means of indicating abnormal displacement to the robot control so that the robot can be stopped before the safety mounting device has reached the limit of its displacement. PA1 6. The safety mounting device should be capable of withstanding the ambient conditions existing near an arc welding operation, such as high temperature, smoke, weld spatter, ozone and high levels of ultra violet and beta radiation. PA1 7. The safety mounting device should be of rugged construction. PA1 8. The safety mounting device should be of minimal weight so as not to compromise the dynamic performance of the robot.
In accordance with a preferred embodiment of this invention there is provided a safety mounting device having all of the desirable characteristics noted above.